title: Hypoxia and gene expression in eukaryotic microbes.
abstract: The response of eukaryotic microbes to low-oxygen (hypoxic) conditions is strongly regulated at the level of transcription. Comparative analysis shows that some of the transcriptional regulators (such as the sterol regulatory element-binding proteins, or SREBPs) are of ancient origin and probably regulate sterol synthesis in most eukaryotic microbes. However, in some fungi SREBPs have been replaced by a zinc-finger transcription factor (Upc2). Nuclear localization of fungal SREBPs is determined by regulated proteolysis, either by site-specific proteases or by an E3 ligase complex and the proteasome. The exact mechanisms of oxygen sensing are not fully characterized but involve responding to low levels of heme and/or sterols and possibly to levels of nitric oxide and reactive oxygen species. Changes in central carbon metabolism (glycolysis and respiration) are a core hypoxic response in some, but not all, fungal species. Adaptation to hypoxia is an important virulence characteristic of pathogenic fungi.
authors.affiliation: School of Biomolecular and Biomedical Science, Conway Institute, University College Dublin, Belfield, Dublin 4, Ireland; email: gbutler@ucd.ie.
authors.forename: Geraldine
authors.initials: G
authors.lastname: Butler
mesh_terms: D000818:Animals; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005658:Fungi / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D009181:Mycoses / Q000378:metabolism / Q000382:microbiology*; D010100:Oxygen / Q000032:analysis / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D010100:Oxygen